Desertification, the loss of the soil's biological productivity, occurs naturally to a limited extent. The pace at which the process has spread recently, however, is largely man's own doing. This fact was highlighted by the great Sahel drought of 1968-73. The worst effects 5 of this drought were caused by nomadic peoples who had earlier been forced by national governments to adopt agricultural and grazing practices that were not in accord with their traditions. In common with those of other nomads around the world, such traditions involved never staying in one place so long as to exhaust the earth that provided 10 them with sustenance. When these people were not allowed to follow this tradition, the process of desertification moved ahead quickly.

1. Which of the following can be said of desertification?(A) It is a wholly natural phenomenon.(B) The Sahel drought was the first example of it.(C) It does not occur naturally.(D) Man has worsened this natural process.2. Where does the author appear to ultimately lay the blame for the effects of the Sahel drought?(A) on nomads around the world.(B) on someone in authority over the Sahel nomads.(C) on natural causes.(D) on the traditions of the Sahel nomads.3. According to the passage, what can be said about the Sahel drought?(A) It lasted for a decade.(B) It emphasized the effects of changing nomadic traditions.(C) It spread to other parts of the world..(D) It forced the adoption of untraditional farming practices.4. Which of the following may be inferred about the author of the passage ?(A) He disapproves of the nomads' traditional attitude to the soil.(B) He approves of the recent pace of desertification.(C) He approves of the nomads' new grazing practices.(D) He approves of the nomads' traditional attitude to the soil.5. Nomads in other parts of the world and the Sahel nomads.(A) share similar customs.(B) share the same desert.(C) suffered particularly in the 1968-73 period.(D) adopted new grazing practices before 1968.